Ashurbanipal's Revenge

About Me

Weazl received a BA in Economics with an emphasis on developing countries from Yale University in the late 80's, then received his JD from Columbia Law School in the early 90's. He has practiced as both a corporate lawyer and as a criminal lawyer for nearly a decade, but currently tries to balance an interest in the esoteric with a need to decipher the moment, howling to the moon that the ship is sinking.

Sunday, September 17, 2006

Human family tree's roots remarkably shallowMath shows common ancestor likely is few thousand years old.

By Matt CrensonASSOCIATED PRESSSunday, September 03, 2006

Whoever it was probably lived a few thousand years ago, somewhere in East Asia; Taiwan, Malaysia and Siberia all are likely locations. He — or she — did nothing more remarkable than be born, live, have children and die.

Yet this was the ancestor of every person now living on Earth, the last person in history whose family tree branches out to touch all 6.5 billion people on the planet today.

Haraz N. GhanbariASSOCIATED PRESS(enlarge photo)

Steve Olson traced his own family genealogy while researching his book 'Mapping Human History' on the origins of our species.

Bebeto Matthews'04 ASSOCIATED PRESS(enlarge photo)

Many today can link ancestries to Alexander the Great, whose offspring spread as he conquered.

That means everybody on Earth descends from somebody who was around as recently as the reign of Tutankhamen, maybe even during the Golden Age of ancient Greece. There's even a chance that our last shared ancestor lived at the time of Christ.

"It's a mathematical certainty that that person existed," said Steve Olson, whose 2002 book, "Mapping Human History," traces the history of the species since its origins in Africa more than 100,000 years ago.

It is human nature to wonder about our ancestors: who they were, where they lived, what they were like. People trace their genealogy, collect antiques and visit historical sites hoping to capture just a glimpse of those who came before, to locate themselves in the sweep of history.

But few people realize just how intricately that web connects them not just to people living on the planet today, but to everyone who ever lived.

With the help of a statistician, a computer scientist and a supercomputer, Olson has calculated just how interconnected the human family tree is. You would have to go back in time only 2,000 to 5,000 years — and probably on the low side of that range — to find somebody who could count every person alive today as a descendant.

Furthermore, Olson and his colleagues have found that if you go back a little further, about 5,000 to 7,000 years ago, everybody living today has the same set of ancestors. In other words, every person who was alive at that time is either an ancestor to all 6 billion people living today or their line died out and they have no remaining descendants.

That revelation is especially startling, statistician Jotun Hein of England's Oxford University wrote in a commentary on the research published by the journal Nature.

"Had you entered any village on Earth in around 3000 B.C., the first person you would have met would probably be your ancestor," Hein marveled.

It also means that all of us have ancestors of every color and creed. Every Palestinian suicide bomber has Jews in his past. Every Sunni Muslim in Iraq is descended from at least one Shiite. And every Klansman's family has African roots.

How can this be?

It's simple math. Every person has two parents, four grandparents and eight great-grandparents. Keep doubling back through the generations — 16, 32, 64, 128 — and within a few hundred years, you have thousands of ancestors.

It's nothing more than exponential growth combined with the facts of life. By the 15th century, you've got a million ancestors. By the 13th, you've got a billion. Sometime around the ninth century, just 40 generations ago, the number tops a trillion.

But wait. How could anybody, much less everybody, alive today have had a trillion ancestors living during the ninth century?

The answer is, they didn't.

Imagine there was a man living 1,200 years ago whose daughter was your mother's 36th great-grandmother and whose son was your father's 36th great-grandfather. That would put him on two branches on your family tree, one on your mother's side and one on your father's.

In fact, most of the people who lived 1,200 years ago appear not twice, but thousands of times, on our family trees because there were only 200 million people on Earth back then. Simple division — a trillion divided by 200 million — shows that on average, each person back then would appear 5,000 times on the family tree of every single individual living today.

But things are never average. Many of the people who were alive in the year 800 never had children; they don't appear on anybody's family tree. Meanwhile, more prolific members of society would show up many more than 5,000 times on a lot of people's trees.

Keep going back in time, and there are fewer and fewer people available to put on more and more branches of the 6.5 billion family trees of people living today. It is mathematically inevitable that at some point, there will be a person who appears at least once on everybody's tree.

But don't stop there; keep going back. As the number of potential ancestors dwindles and the number of branches explodes, there comes a time when every single person on Earth is an ancestor to all of us, except the ones who never had children or whose lines eventually died out.

And it wasn't all that long ago.

When you walk through an exhibit of ancient Egyptian art from the time of the pyramids, everything there was very likely created by one of your ancestors: every statue, hieroglyph and gold necklace. If there is a mummy in the center of the room, that person was almost certainly your ancestor, too.

It means when Muslims, Jews or Christians claim to be children of Abraham, they are all bound to be right.

"No matter the languages we speak or the color of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who labored to build the Great Pyramid of Khufu," Olson and his colleagues wrote in the journal Nature.

How can they be so sure?

Seven years ago, one of Olson's colleagues, a Yale University statistician named Joseph Chang, started thinking about how to estimate when the last common ancestor of everybody on Earth today lived. In a paper published by the journal Advances in Applied Probability, Chang showed that there is a mathematical relationship between the size of a population and the number of generations back to a common ancestor.

Plugging the planet's current population into his equation, he came up with just over 32 generations, or about 900 years.

Chang knew that answer was wrong because it relied on some common, but inaccurate, assumptions that population geneticists often use to simplify difficult mathematical problems.

For example, his analysis pretended that Earth's population has always been what it is today. It also assumed that individuals choose their mates randomly. And each generation had to reproduce all at once.

Chang was fully aware of the inaccuracy. People have to select their partners from the pool of individuals they have actually met, unless they are entering into an arranged marriage.

But even then, they are much more likely to mate with partners who live nearby. And that means that geography can't be ignored if you are going to determine the relatedness of the world's population.

A few years later, Chang was contacted by Olson, who had started thinking about the world's interrelatedness while writing his book. They started corresponding and soon included in their deliberations Douglas Rohde, a Massachusetts Institute of Technology neuroscientist and computer expert who now works for Google Inc.

The researchers knew they would have to account for geography to get a better picture of how the family tree converges as it reaches deeper into the past. They decided to build a massive computer simulation that would essentially re-enact the history of humanity as people were born, moved from one place to another, reproduced and died.

The model also had to allow for migration based on what historians, anthropologists and archaeologists know about how frequently past populations moved both within and between continents.

Rohde, Chang and Olson chose a range of migration rates, from a low level where almost nobody left their native home to a much higher one where up to 20 percent of the population reproduced in a town other than the one where they were born, and one person in 400 moved to a foreign country.

Allowing very little migration, Rohde's simulation produced a date of about 5000 B.C. for humanity's most recent common ancestor. Assuming a higher, but still realistic, migration rate produced a shockingly recent date of about 1 A.D.

Some people even suspect that the most recent common ancestor could have lived later than that.

"A number of people have written to me making the argument that the simulations were too conservative," Rohde said.

Migration is the key. When a people have offspring far from their birthplaces, they essentially introduce their entire family lines into their adopted populations, giving their immediate offspring and all who come after them a set of ancestors from far away.

People tend to think of preindustrial societies as places where this sort of thing rarely happened, where virtually everyone lived and died within a few miles of the place where they were born.

But history is full of examples that belie that notion.

Take Alexander the Great, who conquered every country between Greece and northern India, siring two sons along the way by Persian mothers. Consider Prince Abd Al-Rahman, son of a Syrian father and a Berber mother, who escaped Damascus after the overthrow of his family's dynasty and started a new one in Spain. The Vikings, the Mongols and the Huns all traveled thousands of miles to burn, pillage and — most pertinent to genealogical considerations — rape more settled populations.

More peaceful people moved around as well.

During the Middle Ages, the Gypsies traveled in stages from northern India to Europe. In the New World, the Navajo moved from western Canada to their current home in the American Southwest. People from East Asia fanned out into the South Pacific Islands, and Eskimos frequently traveled back and forth across the Bering Sea from Siberia to Alaska.

One ancestral link to another cultural group among your millions of forbears, and you share ancestors with everyone in that group.

So everyone who reproduced with somebody who was born far from their own birth home — every sailor blown off course, every young man who set off to seek his fortune, every woman who left home with a trader from a foreign land — as long as they had children, they helped weave the tight web of brotherhood we all share.

Writing on Stone May Be Oldest in the Americas

By JOHN NOBLE WILFORDPublished: September 14, 2006

A stone slab found in the state of Veracruz in Mexico bears3,000-year-old writing previously unknown to scholars, according toarchaeologists who say it is an example of the oldest script everdiscovered in the Western Hemisphere.

The order and pattern of carved symbols appeared to be that of atrue writing system, according to the Mexican scientists who havestudied the slab and colleagues from the United States. It hadcharacteristics strikingly similar to imagery of the Olmeccivilization, considered the earliest in pre-Columbian America,they said.

Finding a heretofore-unknown writing system is a rare event. One ofthe last such discoveries, scholars say, was the Indus Valleyscript, identified by archaeologists in 1924.

The inscription on the stone slab, with 62 distinct signs, some ofthem repeated, has been tentatively dated to at least 900 B.C., andpossibly earlier. That is 400 years or more before writing had beenknown to exist in Mesoamerica, the region from central Mexicothrough much of Central America ? and by extension, to existanywhere in the Hemisphere.

Scientists had not previously found any script that wasunambiguously associated with the Olmec culture, which flourishedalong the Gulf of Mexico in Vera Cruz and Tobasco well before theZapotec and Maya people rose to prominence elsewhere in the region.Until now, the Olmec were known mainly for the colossal stone headsthey created and displayed at monumental buildings in their rulingcities.

The inscribed stone slab was discovered by Maria del CarmenRodriguez of the National Institute of Anthropology and History ofMexico and by Ponciano Ortiz of Veracruz University. Thearchaeologists, who are husband and wife, are the lead authors ofthe report of the find, which will be published Friday in thejournal Science.

The signs incised on the 26-pound stone, the researchers said inthe report, “link the Olmec to literacy, document an unsuspectedwriting system and reveal a new complexity to this civilization.”

Noting that the text “conforms to all expectations of writing,” theresearchers wrote that the sequences of signs reflected “patterns oflanguage, with the probable presence of syntax andlanguage-dependant word orders.” Several paired sequences of signs,scholars said, have prompted speculation that the text may containcouplets of poetry.

Experts who have examined the symbols on the stone slab said theywould need many more examples before they could hope to decipherthem and read what is written. It appeared, they said, that thesymbols in the inscription were unrelated to later Mesoamericanscripts, suggesting that this Olmec writing might have beenpracticed for only a few generations and may never have spread tosurrounding cultures.

Stephen D. Houston of Brown University, a co-author of the reportand an authority on ancient writing systems, acknowledged that thiswas a puzzle, and would probably be emphasized by some scholars whoquestion the influence of the Olmec on the course of laterMesoamerican cultures.

But Dr. Houston called the discovery tantalizing, saying, “It couldbe the beginning of a new era of focus on the Olmec civilization.”

Other participants in the research include Michael D. Coe of Yale;Karl A. Taube of the University of California, Riverside; andAlfredo Delgado Calderon of the National Institute of Anthropologyand History.

Mesoamerica researchers who were not involved in the Veracruzdiscovery agreed that the signs appeared to be a true script, andthat the slab could be expected to inspire more intensive study ofthe Olmecs, whose civilization emerged about 1200 B. C. and had allbut disappeared by 400 B. C.

In an accompanying article in Science, Mary Pohl, an anthropologistat Florida State University who has excavated Olmec ruins, wasquoted as saying, “This is an exciting discovery of greatsignificance.”

A few other researchers were skeptical of the dating of theinscription, noting that the stone was uncovered in a gravel quarrywhere it and other artifacts were jumbled and may have been out oftheir original context.

The discovery team said that ceramic shards, clay figurines andother broken artifacts accompanying the stone appeared to be from aparticular phase of Olmec culture that ended about 900 B. C. Butthey acknowledged that the disarray at the site made it impossibleto determine whether the stone had originally been in a placerelating to the governing elite or to religious ceremony.

Richard A. Diehl, a specialist in Olmec research at the Universityof Alabama and another co-author of the report, said, “Mycolleagues and I are absolutely convinced the stone is authentic.”

The stone slab first came to light in 1999, when road buildersdigging gravel came across it among debris from an ancient mound atCascajal, a place the archaeologists called the “Olmec heartland.”The village is on an island in southern Veracruz about a mile fromSan Lorenzo, where ruins have been found of the dominant Olmeccity, which stood from 1200 B. C. to 900 B. C.

When the stone surfaced, Dr. Rodriguez and Dr. Ortiz were calledin, and quickly recognized the potential importance of the find.

Only after six years of further excavations searching for morewriting specimens, and comparative analysis with previously knownOlmec iconography, did the two archaeologists invite otherMesoamerica scholars to join the study earlier this year. Thoughsome other reported examples of Olmec “writing” in recent yearsfailed to stand up to scrutiny, the team concluded that theCascajal stone, as it is being called, was the real thing.

The tiny, delicate symbols are incised on the concave top surfaceof a block of soft stone that measures about 14 inches long, 8inches wide and 5 inches thick.

Dr. Houston, who was a leader in deciphering Maya writing, examinedthe stone looking for clues that the symbols were true writing andnot just iconography unrelated to a language. He said in aninterview that he detected regular patterns and order, suggesting“a text segmented into what almost look like sentences, with clearbeginnings and clear endings.”

Some of the pictographic signs were frequently repeated, Dr.Houston said, particularly ones that looked like an insect or alizard. He suspected that these might be signs alerting the readerto the use of words that sound alike but have different meanings -as in the difference between “I” and “eye” in English.

All in all, Dr. Houston concluded, “the linear sequencing, theregularity of signs, the clear patterns of ordering, they tell methis is writing. But we don’t know what it says.”